Final answer:
Rice is the staple crop most vulnerable to sea level rise because it is often grown in low-lying river deltas, which are susceptible to flooding that can damage or destroy crops.
Step-by-step explanation:
The staple crop that is particularly vulnerable to the effects of sea level rise is b) Rice. Rice is commonly grown in river deltas, which are low-lying areas close to sea level. For example, the fertile deltas of the Ganges and Brahmaputra Rivers in Bangladesh, which empty into the Bay of Bengal, are prime locations for rice cultivation. However, these areas are at high risk of flooding due to sea level rise, which could erode soil and wash away the crops, thereby threatening rice production and food supply.