Vectors that can spread disease to humans include:

a. Mosquitos
b. Ticks
c. Rabbits
d. All of the above
e. A and B only

Answer is option E (A and B only).

Explanation:

Vectors are any living organisms or agents that carries and transmits pathogens that can cause infectious diseases between other living organisms. They are mostly bloodsucking insects like mosquitoes, fleas, ticks, sandflies, bugs, lice and some freshwater aquatic snails. Some parasitic plants and fungi acts as vectors for plant pathogens.

When the blood sucking insects feed from an infected host (human or animal), pathogen enters their blood stream and during their next feed it is transmitted into a new host. The examples of various vectors and some of the diseases they spread in humans and other animals are;

Anopheles mosquitoes - Malaria , Lymphatic filariasis.Aedes  mosquitoes  - Dengue fever , Zika , Chikungunya , Yellow fever , Lymphatic filariasis .Culex  mosquitoes - West Nile fever , Lymphatic filariasis , Japanese encephalitis .Ticks  - Lyme disease , Tularaemia , Crimean-Congo haemorrhagic fever , Tick-borne encephalitis , borreliosis.Fleas  - Rickettsiosis , Plague.Sandflies  - Phelebotomus fever, Leishmaniasis.Lice  - Typhus, Louse-borne relapsing fever.Triatomine bugs  - Chagas disease.Black flies  - Onchocerciasis.Aquatic snails  - Schistosomiasis.

The risk  of transmission of zoonotic disease from rabbits to humans is considered very low, but certain diseases such as encephalitozoonosis, dermatophytosis, rabies, etc carried by rabbits can be potentially transmitted to humans. Some zoonotic diseases such as tularemia (rabbit fever), lyme disease, etc are very rarely transmitted by fleas and ticks (vectors) into humans and  animals, and such infection can be subclinical or may cause flu-like signs or pneumonia.

If you remove all the lions from the savanna it will lead to a increase of gazelle and a increase of cheetahs becasue of no competition

Dna strands are split apart to allow an opening for replication. the opening has two replication forks so synthesis goes toward them in 5' to 3' direction.