The answer is c.) doctor's
To show procession of the patients by the doctor add 's to the word doctor.
To fix the sentence, change "," after 2004 to ";" and remove the "and" before scientists. It makes the sentence sound better.
I hope that helps!
11. mosquitos or mosquitoes
12.sopranos
13. echos or echoes
14.mice
15.Heroes
16.children
17.Oxen
18.thousand
19.t's
20.shelves
21.beliefs
22.cries
23.monkeys
24.father-in-law
25.sheep
26.pianos
27.spoonfuls
28 eskimos
29.knives
30.clutches
31.radios
32.potatoes
33.lasses
34.altos
35.and
36.babies
37.chefs
38.arpeggios
39.pulleys
40.waxes
41.lunches
42.counties
43. deer
44.boys
45.women
46.men-at-arms
47.dragonflies
48.benches
49.grasses
50.sailfishes
