Matching.

1. retina contains receptors for hearing
2. cochlea sometimes called the fifth sense; associated with monosodium glutamate and high-protein foods
3. taste buds a physical stimulus is converted into nerve impulses
4. transduction changes light rays into neural impulses
5. umami the ability to taste sweet, salty, sour and bitter flavors.

Retina changes light ray into neural impulses

Cochlea contains receptors for hearing

Taste buds the ability to taste sweet, salty, sour and bitter flavors

Transduction  a physical stimulus is converted to neural impulses

Umami sometimes called the fifth sense; associated with mono-sodium glutamate and high-protein food

Explanation:

they all focused on themes about the inevitability of death.

d. i assume the underlined word is "role." reformat if it isn't.

explanation:

role is closest to part because when replacing words, "playing a vital decision," "playing a vital activity," and "playing a vital dollar" don't make logical sense. the only meaningful choice is "playing a vital part."

this fits one of merriam-webster's definitions of role: "a function or part performed especially in a particular operation or process."