Programmable controllers (PLCs): which statements are accurate about their programming and industry adoption? Choose the best combined option.

Introduction / Context:
Programmable controllers dominate discrete and process automation across manufacturing, energy, water, building systems, and more. Their success rests on pragmatic programming models and robust hardware designed for industrial environments.

Given Data / Assumptions:

• PLCs historically support relay ladder logic due to workforce familiarity.
• Modern PLCs also support other IEC 61131-3 languages.
• Adoption spans multiple sectors worldwide.

Concept / Approach:
While PLCs are frequently programmed in ladder logic, they are not limited to relay-type operations. Today’s platforms implement timers, counters, math, motion control, PID, communications, and safety functions, delivered through ladder, function block diagrams, structured text, and sequential function charts. Therefore, statements (a) and (c) are collectively true, whereas (b) is false.

Step-by-Step Solution:
Evaluate (a): true—ladder logic remains common and supported.Evaluate (b): false—PLCs perform many non-relay functions.Evaluate (c): true—PLCs are widely used across industries.Select the combined option (a) and (c).

Verification / Alternative check:
Vendor catalogs show extensive application libraries and multi-language support, reinforcing that PLCs go far beyond simple relay replacement while remaining broadly adopted.

Why Other Options Are Wrong:
(a) alone ignores breadth of adoption; (c) alone ignores programming reality; (b) is incorrect; “None” is invalid because a correct combined option exists.

Common Pitfalls:
Equating ladder logic with limited functionality; modern instructions and modules enable sophisticated control within ladder-based projects.

Final Answer:
(a) and (c) above