system: You are an expert security code reviewer. You will be shown a source code file along with a multiple-choice question listing several function or class names from that file. Your task is to identify which one contains the specified CWE vulnerability.

OUTPUT FORMAT: Respond with the single letter of the correct option, wrapped in \boxed{...}. Example: `\boxed{B}`. Output the boxed letter ONLY -- no explanation, no other text.

user: ```python
"""Contains serializers for the abstract tasks models."""

from django.core.exceptions import ValidationError
from rest_framework import serializers
from tasksapi.models import AbstractTaskInstance, AbstractTaskType
from tasksapi.utils import get_allowed_queues_sorted


class AbstractTaskTypeSerializer(serializers.ModelSerializer):
    """A serializer for a task type."""

    user = serializers.SlugRelatedField(slug_field="username", read_only=True)

    class Meta:
        # Make sure you change this in the subclass serializer!
        model = AbstractTaskType

        fields = "__all__"

    def to_internal_value(self, data):
        """Inject the user into validation data.

        Need to inject it here before the UniqueTogether validator runs.
        See discussion here:
        https://stackoverflow.com/questions/27591574/order-of-serializer-validation-in-django-rest-framework.
        """
        data = super().to_internal_value(data)
        data["user"] = self.context["request"].user
        return data

    def validate(self, attrs):
        """Ensure the argument fields passed in are valid.

        Relies on the model's clean method. Note that the object-level
        validation used here effectively precludes being able to
        validate partial updates, due to lack of support in DRF for
        object-level validation in partial updates.
        """
        # Call parent validate method
        attrs = super().validate(attrs)

        # Be careful with optional arguments
        try:
            required_args = attrs["required_arguments"]

            assert required_args is not None
        except (KeyError, AssertionError):
            required_args = []

        try:
            default_vals = attrs["required_arguments_default_values"]

            assert default_vals is not None
        except (KeyError, AssertionError):
            default_vals = {}

        try:
            environment_vars = attrs["environment_variables"]

            assert environment_vars is not None
        except (KeyError, AssertionError):
            environment_vars = []

        # Test instance
        try:
            test_type_instance = AbstractTaskType(
                user=attrs["user"],
                name=attrs["name"],
                command_to_run=attrs["command_to_run"],
                environment_variables=environment_vars,
                required_arguments_default_values=default_vals,
                required_arguments=required_args,
            )
            test_type_instance.clean()
        except ValidationError as e:
            raise serializers.ValidationError(str(e))

        return attrs


class AbstractTaskInstanceSerializer(serializers.ModelSerializer):
    """A serializer for reading a task instance."""

    user = serializers.SlugRelatedField(slug_field="username", read_only=True)

    def __init__(self, *args, **kwargs):
        """Initialize the queryset for task queues."""
        # Call parent constructor
        super().__init__(*args, **kwargs)

        # Customize the queryset of the task queues to only include
        # allowed queues. If a bad task type for a queue is chosen the
        # task instance model validation will deal with it; we can't do
        # anything more here without having a particular task in hand.
        if "context" in kwargs:
            self.fields["task_queue"].queryset = get_allowed_queues_sorted(
                user=kwargs["context"]["request"].user
            )

    class Meta:
        # Make sure you change this in the subclass serializer!
        model = AbstractTaskInstance

        read_only_fields = ("state",)
        fields = "__all__"

    def validate(self, attrs):
        """Ensure the arguments fields passed in are valid.

        Relies on the model's clean method. Note that the object-level
        validation used here effectively precludes being able to
        validate partial updates, due to lack of support in DRF for
        object-level validation in partial updates.
        """
        # Call parent validate method
        attrs = super().validate(attrs)

        # Be careful with optional arguments
        try:
            arguments = attrs["arguments"]

            assert arguments is not None
        except (KeyError, AssertionError):
            attrs["arguments"] = {}

        # Make sure to do a test like the following in the subclass'
        # validate method. Call super() first, please :)
        #
        # try:
        #     test_instance = AbstractTaskInstance(
        #         user=self.context['request'].user,
        #         task_type=attrs['task_type'],
        #         task_queue=attrs['task_queue'],
        #         arguments=attrs['arguments'],)
        #     test_instance.clean()
        # except ValidationError as e:
        #     raise serializers.ValidationError(str(e))

        return attrs

```

Which of the following functions or classes contains a `CWE-209: Generation of Error Message Containing Sensitive Information` vulnerability?

  A) __init__
  B) to_internal_value
  C) AbstractTaskTypeSerializer
  D) validate
Answer: D