What is wrong with the following sentence?
Being unable to type the letter, the boss fired me.
a. properly constructed sentence
b. Comma splice
c. Dangler
d. Fragment

My answer is d

Which one of the following items is a complete sentence?
a. The receptionist, who was away last week.
b. The receptionist returning to work today.
c. The receptionist returns today.
d. The receptionist, who was away last week and returns to work.

My answer is c

Identify the grammatical error int he following sentence?

Helen went to wrok, Bob went home.
a. This sentence is a fragment
b. This sentence is a dangler.
c. This sentence contains a comma splice.
d. This sentence lasck parallel parts.

I am not sure between a & c

Which one of the following sentence contains a dangling modifier?
a. Sitting on th ewindowsill. the geraniums got lot of sunshine.
b. Before going home, this account must be audited.
c. Jogging quickly around the track, Janice was becoming breathless.
d. To get the best results, follow the directions on the label closely.

I am not sure between a & c

If my answers are wrong please let me know why. I had a hard time with this section.

Thank you for your assistance. I just want to know if I am understanding this lesson correctly.