What causes the softening of the cell wall and the breaking of sugars? Ethylene.
Cytokinins
Auxin.

Ethylene

Explanation:

Introduction

The growth and development of plants under varied environmental conditions determine agricultural production. The growth, development, and senescence of plant’s organs can influence crop production by modulating photosynthesis, nutrient remobilization efficiency, and harvest index (Paltridge et al., 1984; Jing et al., 2005; Iqbal et al., 2012). Phytohormones have been shown to increase growth and yield of plants. The phytohormone ethylene controls growth and senescence of plants (Reid, 1995; Lutts et al., 1996; Thompson et al., 1998; Pierik et al., 2006; Masood et al., 2012; Nazar et al., 2014). Ethylene is regarded as a multifunctional phytohormone that regulates both growth, and senescence. It promotes or inhibits growth and senescence processes depending on its concentration, timing of application, and the plant cell

succession returns a disturbed

ecosystem to a more stable state. this is also classified into two (2) types:

primary succession and secondary succession. the primary succession arises when

a new land is transformed and a bare rock has been exposed providing an environment

that can be occupied for the first time. while, secondary succession occurs

when a previously occupied environment was disturbed that kills much of all its

community

explanation:

the answer would be..

b. sucking