Directions: In the sentence below, four parts labeled (A), (B), (C), and (D) are given in a jumbled order. Rearrange these parts to form a contextually and grammatically coherent sentence. If the sentence is already in the correct order, select 'No rearrangement required'.

(A) force was required,

(B) such as textile mills and iron foundries

(C) steam power was the primary energy source in

(D) industries where continuous mechanical

The correct option is CDAB.

To form a contextually and grammatically coherent sentence, let us analyze the given jumbled parts step-by-step:

1. Part (C): "steam power was the primary energy source in"
This part acts as the primary subject and predicate, introducing the central topic ("steam power") and setting up the preposition "in".

2. Part (D): "industries where continuous mechanical"
This part follows (C) seamlessly to complete the prepositional phrase ("in industries...") and introduces a relative clause describing those industries ("where continuous mechanical...").

3. Part (A): "force was required,"
This part naturally completes the phrase "continuous mechanical" from part (D) to form "continuous mechanical force was required,".

4. Part (B): "such as textile mills and iron foundries"
This part provides concrete examples ("such as textile mills and iron foundries") of the industries referenced in part (D).

Putting all the parts together in the sequence C → D → A → B forms a complete, meaningful sentence:
"Steam power was the primary energy source in industries where continuous mechanical force was required, such as textile mills and iron foundries."

Therefore, the correct sequence of arrangement is CDAB.