Directions: In the question given below, a sentence is presented with four highlighted words labelled (A), (B), (C), and (D). These words may not be placed in their correct positions. Select the option that indicates the correct combination of words that need to be interchanged to render the sentence grammatically correct and contextually meaningful.

The city is infrastructure (A) upgrading its public transport steadily (B), and automated signaling offers a remarkable network (C) to optimize this breakthrough (D).

The correct option is A-B and C-D.

Let's analyze the highlighted words in the sentence step-by-step:
1. In the first clause: "The city is infrastructure (A) upgrading its public transport steadily (B)..."
- "Infrastructure" is a noun placed where an adverb is required to modify the verb "upgrading".
- "Steadily" is an adverb currently modifying nothing appropriate at the end of the phrase.
- Interchanging (A) and (B) places "steadily" before "upgrading" and "infrastructure" after "public transport", creating the correct phrase "steadily upgrading its public transport infrastructure".

2. In the second clause: "...and automated signaling offers a remarkable network (C) to optimize this breakthrough (D)."
- Contextually, automated signaling itself is a "breakthrough", and the transport system being optimized is the "network".
- Interchanging (C) and (D) gives "offers a remarkable breakthrough to optimize this network".

Thus, by swapping A-B and C-D, the sentence becomes grammatically correct and contextually meaningful:
"The city is steadily upgrading its public transport infrastructure, and automated signaling offers a remarkable breakthrough to optimize this network."