Dolphins communicate using compression waves. Some of these sounds are outside the range of human hearing. Upon spotting a hungry shark, dolphin A sends a message to dolphin B. To send this message as quickly as possible, dolphin A would

half of a circle

explanation:

the arrow and the top of the circle is matching together. it is not a polygon because a polygon would always be the same shape. therefore, an half of a circle is called semicircle so you would find the radius of it.

real, smaller and upside-down.   so the answer should be b.

current and voltage can both be different in different parts of a circuit so it matters where you place the ammeter and voltmete

i think it's 35 meters